Teletypewriter apparatus



July 16, 1940. w. G. SKIBSTED TELETYPEWRITER APPARATUS Filed Oct. 8, 1938 POLAR/ZED lNl/ENTOR By W. G. SK/BSTED A TTO/P/VE V Patented July 16, 1940 PATENT OFFICE TELETYPEWRITER APPARATUS Wesley George Skibsted, Miami, Fla., assignor to American Telephone and Telegraph Company, a corporation of New York Application October 8, 1938, Serial No. 234,005

3 Claims.

This invention relates to printing telegraph systems and, more particularly, to printing telegraph exchange systems having subscribers teletypewriter stations which are occasionally left unattended and which are provided with motor control devices.

In a system of this type, the subscribers teletypewriters are each usually continuously connected to an individual local source of alternating current for energizing their motor-generators to supply direct current for operating the teletypewriters. This connection is usually maintained during the time that a station is left unattended so that the subscribers teletypewriters can be operated by remote control. Sometimes interruptions or large fluctuations in the local alternating current supply will effect unintended operation of a subscribers teletypewriter motor control device with the result that the subscribers motor will be started thereby causing wasteful power consumption and needless wear of the subscribers teletypewriter apparatus.

Accordingly, it is an object of this invention to provide means for preventing irregularities in the flow of current from the local alternating current power supply from unintentionally start ing the motor of a subscribers teletypewriter.

It is also an object of the invention toprovide an unattended subscribers teletypewriter with a relay having a blocking pin aiiixed to its armature for blocking unintended operation of the motor control lever in the teletypewriter and thereby preventing the teletypewriter motor from starting accidentally.

These objects are attained by connecting a relay, having a blocking pin afiixed to its armature, into the subscribers power supply circuit. As long as current continues to flow in this circuit, the relay will remain energized and will maintain its armature operated. However, if an interruption or large fluctuation in the local alternating current power supply should occur, then the relay would release its armature and the blocking pin would fall, under the influence of a push-type spring, behind a latch in the teletypewriter thereby blocking movement of the arm of the motor control lever and thus preventingthe starting of the teletypewriter motor.

The invention will be described in more detail 5 in connection with the following detailed description of the drawing in which:

Fig. l is a three-dimensional perspective view of the added relay with its armature and blocking pin and showing the location of this relay 55 and its blocking pin in respect to the latch of the motor control lever and other portions of the motor control apparatus;

Fig. 2 shows the added relay in its unenergized condition with its armature released and the blocking pin in engagement with the latch of the motor control device;

Fig. 3 shows the added relay in its normally energized condition with its armature operated and the blocking pin withdrawn from engagement with the latch of the motor control device;

Fig. 4 illustrates the degree of movement of the latch of the motor control device; and

Fig. 5 represents the subscribers static-n circuit connections, line circuit, and power circuit.

The invention will now bedescribed with reference to its preferred embodiment as shown in the drawing in which a subscriber is shown to be provided with a teletypewriter, such as that disclosed in Patent 1,904,164 granted April 18, 1933 to S. Morton et al., having a motor control 20 device, such as that disclosed in Patent 1,931,672 granted October 24, 1933 to S. Morton et al. The disclosure of these two Morton et al. patents is incorporated herein by reference as a part of this specification. It is to be understood that the invention is not to be limited to the specific teletypewriter and motor control device disclosed in these Morton et al. patents as the invention can be applied to other forms of apparatus.

The subscribers station A, as shown in Fig. 5, 30 includes a line relay l, sending contacts 2, and break contacts 3 connected directly to a communication channel L extending to a station B which may be either another subscriber's station similar to station A or a teletypewriter central office. The station A is further provided with a local source of alternating current 4 connected through switch 2| to the motor-generator 5, and connectable through the motor control unit 0 to the motor 6. One terminal of the motor-generator 5 is connected to a junction 1 from which two paths extend; one directly to the spacing contact of the line relay l and the other to a junction 8. Two paths extend from junction 8; one through the winding of the selector magnet IE to the marking contact of line relay I, and the other through the winding of control relay 9, Winding of line relay l, and then to junction Ill. From junction In, one path leads to the other terminal of motor-generator 5 and the other path leads to the armature of line relay I.

Since the line L normally has current flowing over it, the line relay I will normally hold its armature on its marking contact thereby closing a path from motor-generator 5 to junction I El, over the armature and marking contact of line relay I, through the winding of selector magnet I6, over junctions 8 and 1, and then back to the other terminal of motor-generator 5. Consequently, selector magnet I6 is normally energized and its armature IT is normally operated.

'When an operator at station E wishes to start the motor 5 at station A, she momentarily opens line L which causes the line relay I to move its armature to its spacing contact thereby deenere gizing selector magnet It and causing the release of armature ll. As is explained in Morton et al. Patent 1,931,672, armature I I, when released, rotates slightly to effect the disengagement of latch Iii-5 from the inside face of extension I8? and also to eiiect the engagement of latch 106 with the step H2 with which extension it? is provided.

The operator at station B then closes the line L to effect the reenergization of selector magnet I6 which again operates its armature Ill. The operation of armature I? actuates its extension IIZ'I vertically thereby lifting step .I I2 out of engagement with latch I88. Latch I05 will now be rocked by the distending action of spring I '39 and will slip oif the upper surface of extension Iill. Until this time, motor control lever QI had its arm IP32, biased to the right by spring m3, held back due to the engagement of latches m5 and IE6 with extension lfi'I. The release of latches I05 and 566, which are pivotally connected to arm IilZ of motor control, or motor stop, lever 95, allows spring I33 to pull arm I62 forward around its pivot H3. The forward movement of arm I92 of motor stop lever 9|, rotatably mounted on U-shaped bracket 9%), causes arm ID! of lever BI to be tilted downward to allow arm 89 of lever 88 to move downward thereby moving arm 92 of lever 83 up to close contact 86. Contact 86 is located in the motor control unit C, as is shown in Fig. 5, and its closure closes a path from the alternating current source 3 for operating motor 6.

After being started in this manner, motor 5 will continue to run until stopped by the method described in the above-mentioned Morton et a1. Patent 1,931,672. When motor 5 is being stopped, contact 81 is closed for a short time, by means described in Morton et al. Patent 1,931,672, to allow the cycle of operations of the teletypewriter apparatus to be completed. During this cycle of operations, contact 86 is opened and, after the cycle is completed, contact 81 is opened. Both contacts 85 and 87 then remain open until motor 6 is again started. Manual switch 2| is provided for enabling the local operator to control the energization of motor-generator 5.

If an interruption or large fluctuation should occur in the alternating current from source 4 and should be followed by a normal flow of current from source t, this would have the same effeet as an opening followed by a closure of the normally closed line L in that selector magnet It would first release its armature I1 and then operate it again. The release of armature I? would disengage latch 695 from extension M37 and the operation of armature I! would lift step H2 of extension I52 out of engagement with latch Itii. As was described above, the release of latches I05 and it from engagement with extension E9? of armature I? allows arm IIlZof motor stop lever St to be pulled forward by spring we to close contact 86 and thereby start motor 6.

To prevent this unintentional starting of motor 6, control relay 9 is positioned in the'subscribers teletypewriter near latchesIllE and I06 and is tached to the top end of armature I4. Mounted in the otherend ofstrip I8 is an adjustable stop 23 for limiting the extent of travel of armature I4 when released by relay 9.

As is shown in Fig. 5, control relay 9 is continuously connected across the terminals of motor-generator 5 for continuous energization and operation of its armature It. Armature I4, when operated compresses push-type spring i9 and moves its blocking pin I5 to the left where, as shown in Fig. 3, its does not interfere with the movement of arm N8 of latch Hi3 attached to arm I62 of motor stop lever 9L Thus, when relay ii is energized, arm. I02 will be free to move forward under the action of its spring 5&3 for starting motor 8 whenever latches I55 and I536 are released. Under these circumstances, if an interruption or large fluctuation should occur in the alternating current from source 4 and should be followed by a normal flow of current, selec tor magnet It will release its armature i 'i which, in turn, will release latches I05 and ififi. However, at the same time, control relay 9 will also release its armature It which, under the action of push-type spring I9, will move to the right to place its blocking pin I5 in the path of movement of arm IIB of latch I95 as is shown in Fig. 2. Thus, even though latches H35 and 596 are released, spring !03 will be unable to pull arm I02 of motor stop lever 9| forward because blocking pin I5 prevents arm N8 of latch Hit from moving forward and, since latch $66 is attached to arm I02, arm I62 is also held back by pin I5.

As soon as normal current flow is resumed in the power circuit, control relay 9 will again be energized and will operate its armature i l to withdraw pin I5 from engagement with arm H8. At the same time, selector magnet IE will be also energized and will operate its armature I? for causing its extension It? to resume engagement with latches I05 to I08 to hold arm I62 from being operated by spring I 03. Consequently, motor 6 is prevented from being unintentionally operated.

This blocking action of pin I5 is further illustrated in Fig. 4 which also shows bysolid and dotted lines the rocking action of latch I0 6. When selector magnet It is energized, latch I06 is held in the position shown in solid lines in Fig. 4 by step H2. Deenergization of magnet It causes the release of armature I! which releases latch E06. Spring m9 then rocks latch lflfi'to the position shown in dotted lines in Fig. 4. However, blocking pin I5 engages at this time with arm H8 oflatch I06 to prevent it from moving to the right.

The invention has been described with reference to its preferred embodiment and its preferred application. It is to be understood that the invention is capable of other applications and may be embodied in other forms of apparatus than that specifically shown in the drawing. Consequently, the invention is not to be limited to the particular form and use shown and described but is to be limited only by the claims appended hereto.

What is claimed is:

1, In a printing telegraph system, a plurality of intercommunicating stations, one of said stations being provided with a printing telegraph machine, a motor for operating said printing telegraph machine, a local source of power supply at that station for operating the motor, a motor controlling circuit also at that station, starting means in said motor controlling circuit controllable by an operator at another station for controlling the supply of power to the motor, blocking means for preventing the operation of the starting means, and operating means for operating said blocking means in response to an irregularity in the local source of power supply.

2. A communication system having a communicating device, a motor for operating said communicating device, a source of power supply, a normally open energizing circuit for connecting the source of power supply to the motor, a motor-generator, means for connecting the motor-generator to the power supply for operation 6 thereby, starting means for closing said energizing circuit for starting the motor into operation by the source of power supply, said starting means including a magnet having an armature and means for energizing the magnet with current supplied by the motor-generator, remote control means for opening the circuit from the motor-generator to the magnet for causing the magnet to release its armature for operating the starting means, control means for preventing release of the armature in response to an irregularity in the flow of current from the motor-generator, said control means including a relay, and means for connecting the relay across the output terminals of the motor-generator, said relay having an armature, an instrumentality attached to the armature of the relay, and means for moving the armature of the relay and said instrumentality in response to the deenergization of the relay for preventing the magnets armature from moving to its released position to operate the starting means.

3. A subscribers teletypewriter station including in combination a teletypewriter, a motor for operating the teletypewriter, a local source of alternating current at the subscribers station, remote control means for connecting the motor to the local source of alternating current for operation thereby, an instrumentality at the subscribers station for controlling the effectiveness of the remote control means, and operating means also at the subscribers station for actuating said instrumentality in response to an irregularity in the alternating current from the local source to prevent the remote control means from connecting the motor to the local source of alternating current.

WESLEY GEORGE SKIBSTED. 

